The invention relates to antennas and more particularly to antennas for use on automotive vehicles such as those used in mobile radio communications.
Automobile antennas, especially those used for cellular mobile radios are commonly lightweight wire antennas designed to operate generally in the 800 to 900 MHz frequency range. Such an antenna may include a coil section referred to as a loading coil connected between substantially straight upper and lower sections. A problem with such antennas is that they tend to bend due to wind force when the vehicle reaches higher speeds. The frequency characteristics of the antenna are determined in large measure by its length and bending of the antenna tends to change its effective length and diminish significantly its efficiency.
Another problem with such antennas having load coils, is that the coil produces an annoying whistle at higher speeds of the vehicle. The coils further tend to be unsightly and there is a need for an aesthetically pleasing antenna design which overcomes the disadvantages of antennas currently on the market.
Furthermore, automobile antennas and particularly mobile radio antennas are prone to be damaged when they are bumped or bent. Such antennas are commonly fastened to a metal part of the car or a window glass in a semipermanent fashion so that they are not readily removed or retracted. Automatic carwashes are of a special concern since they often cause damage to mobile radio antennas.